It is well known in the subterranean well drilling and completion art to perform tests on formations intersected by a wellbore. Such tests are typically performed to determine geological or other physical properties of the formation and fluids provided thereform. For example, parameters such as permeability, porosity, fluid resistivity, temperature, pressure, and bubble point may be determined. These and other characteristics of the formation and fluid may be determined by performing tests on the formation before the well is completed.
One type of testing procedure that is commonly performed is to obtain a fluid sample from the formation to, among other things, determine the composition of the formation fluids. In this procedure, it is important to obtain a sample of the formation fluid that is representative of the fluid as it exists in the downhole environment. In some typical sampling procedures, a sample of the fluid may be obtained by lowering a sampling tool having a sampling chamber into the wellbore on a conveyance such as a wireline, slickline, coiled tubing, jointed tubing or the like. When the sampling tool reaches the desired depth, one or more ports are opened to allow collection of the formation fluids. The ports may be actuated in variety of ways such as by electrical, hydraulic or mechanical methods. Once the ports are opened, formation fluids travel through the ports and a sample of the formation fluids is collected within the sampling chamber of the sampling tool. After the sample has been collected, the sampling tool may be withdrawn from the wellbore so that the formation fluid sample may be analyzed.
It has been found, however, that as the fluid sample is retrieved to the surface, the temperature of the fluid sample decreases causing shrinkage of the fluid sample and a reduction in the pressure of the fluid sample. Once such a process occurs, the resulting fluid sample may no longer be representative of the fluids present in the formation. Therefore, a need has arisen for an apparatus and method for obtaining a fluid sample from a formation without degradation of the sample during retrieval of the sampling tool from the wellbore. A need has also arisen for such an apparatus and method that are capable of being conveyed via a slickline, wireline, or coiled tubing.